Thin-film windows are often required for a detector or probe for a nuclear instrument. Such thin-film windows are used in parallel plate ionization chambers to form one of the plates and also as a window through which x-rays pass through. In such use, it is desirable to have the window of a thin material to minimize attenuation of the x-rays. It is also desirable for the chamber to have a flat response for low-energies, such as those used in mammography. Thus, it is an object of this invention to provide a thin-film window for use in ionization chambers of a material that will minimize attenuation of x-rays and have a flat response at low-energy levels.
In parallel plate ionization chambers, the available space is usually limited. It is thus an object of this invention that the frame holding the window be as small as possible to minimize x-ray scattering from the frame into the sensitive volume between the parallel plates. The frame must however be able to maintain a taut uniform stretching of the thin-film window.
Thin-filmed windows used in nuclear instruments are frequently subjected to severe temperature and pressure changes which occur during transport of the window, and it is a further object of this invention to provide a window that is able to withstand the severe temperature and/or pressure changes.
It is still further an object of this invention to provide a method of making a thin-film window having the above mentioned properties.